Abstract: Method and system aspects for searching for an optimal codevector from a plurality of codevectors in a codebook, the optimal codevector having a minimum distance to a given vector, are provided. The aspects determine a partial distance with a current vector component of a current codevector and of the given vector, compare the partial distance to a saved renormalized minimum partial distance, and proceed to a next codevector when the saved renormalized minimum partial distance is smaller than the partial distance. In addition, the present invention proceeds to a next vector component when the partial distance is smaller than the saved renormalized minimum partial distance. When the partial distance computed with each next vector component is smaller than the saved renormalized minimum partial distance, the present invention calculates a full weighted distance value, compares it to a saved minimum full weighted distance, and updates chosen values.

Abstract: In a digital signal processing system, a method for selecting a transform function to apply to an input signal based on characteristics of the signal, and for self-adjusting criteria which are used in selecting a transform function to apply to a subsequent signal. Characteristics are obtained from the signal. The characteristics are compared to adjustable criteria which are used in selecting a transform function. Differing criteria are maintained for the different selectable transform functions. A record is maintained of transform functions selected and the particular characteristics that caused the selection. Based on the ability of a transform function to minimally define the coded signal, an inverse transform function is selected to decode the signal. The criteria used in selecting a transform function to apply to a subsequent signal are adjusted based on a quality measure of the decoded signal and the record of selected transform functions.

Abstract: A decompression approach utilizing a single buffer to reduce working memory space decompression requirements. Loading a compressed data file into the "back end" of a buffer and progressively loading the resulting decompressed data into the "front end" of the buffer avoids allocating multiple buffers for the decompression process. Using a slop value to increase the size of the allocated buffer beyond the original uncompressed data size avoids inadvertently overwriting not yet uncompressed data still residing in the back end of the single buffer when storing just decompressed data in the front end of the single buffer.

Abstract: A communication system encodes input data by comparing the data to records in a lossy codebook to determine the closest match. An index corresponding to the record that most closely matches the input data is retrieved from the codebook and transmitted to a receiver. For a predetermined sampling interval, the communication system collects statistics of the frequency of occurrence of each record matching the input data. The records are sorted in descending order by the frequency of occurrence. Using either a predetermined error rate or a predetermined subtable size, the communication system creates a subtable of the records having the greatest frequency of occurrence. To reduce the search time of finding a record matching the input data, the communication system searches only the subtable for records until the error of the match in the subtable exceeds a preselected threshold or until a preselected period of time has elapsed. The communication system again collects statistics of the frequency of occurrence.

Abstract: A system for estimating block motion from a previous frame to a current frame, wherein motion vectors have been computed for blocks in the previous frame. The system comprises a P-checkerboard processor, an S-checkerboard processor and a block matching engine. The a P-checkerboard processor selects a first current block from a primary checkerboard pattern, retrieves motion vectors for reference blocks in the previous frame, and uses the retrieved motion vectors to generate a temporal search window. The block matching engine locates in the temporal search window a block which best matches the first current block, and determines the current motion vector from the best matching block to the first current block. Alternatively, the a P-checkerboard processor can use the retrieved motion vectors to interpolate the current motion vector. The S-checkerboard processor selects a second current block from a secondary checkerboard pattern, and uses the current motion vector to generate a spatial dynamic search window.

Abstract: A method for improved recursive pitch prediction includes providing a search window for pitch estimates based upon a previously computed pitch, computing pitch estimates for the search window, and determining an optimal pitch from the pitch estimates within the search window for a first predetermined number of frames. The method further includes expanding the search window to a full pitch window after the first predetermined number of frames, and calculating pitch estimates for the full pitch window for a second predetermined number of frames.A system for improved recursive pitch prediction includes a speech generator of speech signals, and a central processing unit coupled to the speech generator.

Abstract: Method and system aspects for linear predictive speech encoding are disclosed. These aspects comprise the definition of an error function, the computation of an optimal vector of continuous pitch coefficients together with an optimal pitch, and the weighted vector quantization of the continuous pitch coefficients. The techniques allows the faster computation of the optimal combination pitch--continuous coefficient values without substantial loss of optimal results.

Abstract: Storage and access of compressed data via separately compressed and stored variable size logical blocks. Portions of a data file are compressed until they reach a logical block size which matches a given sector size or block of storage space. The compressed logical block (portion of compressed data) is stored into a sector allocated to it and a table is built correlating the range of original data to the sector storing the compressed data. When it is desired to read a given portion of data within a stored compressed data file, it is first determined where within the original data file the desired portion resided. Then, the correlation table created as part of the compression and storage sequence is used to determine which sector contains the desired data.

Abstract: A signal processing system determines the characteristic of a signal for encoding or decoding by examining and classifying such signal, and then applies a transformation or inverse transformation to such signal. Depending on classification of the signal, various transforms or inverse transforms are applicable adaptively thereto.

Abstract: Storage and access of compressed data via separately compressed and stored fixed size logical blocks. An original uncompressed data file is divided into fixed-size logical blocks and then separately compressed thus resulting in a compressed block of data of a generally known maximum size according to a compression ratio known in advance of the actual compression. After the uncompressed fixed-size logical block has been compressed into a maximum fixed-size logical block it is stored into space allocated to it. Furthermore, a table is built correlating the original uncompressed fixed-size logical block to the sectors allocated for each maximum fixed-size compressed logical block thus providing a mapping between the original uncompressed data file and the physical location on the storage device. Alternatively, because the compression ratio is known and because the size of the uncompressed fixed-size logical blocks is known, the resulting maximum size of the compressed logical blocks is generally known.

Abstract: An efficient speed trie search process which generates a sequence of pointers for each family of children in a trie, the sequences of pointers being organized in a predefined order according to a detected data type information of the input data stream. In response to the detected data type information, the trie search process selects a pointer sequence organization from one or more predefined organization sequences, such as an organization sequence from the most recently matched data in a family of nodes to the least recently matched data in that family of nodes, an organization in accordance to a predetermined frequency distribution of a predefined set of data symbol, or an adaptive frequency distribution sequence of a set of symbols detected in an input data stream. Such arrangement of pointers, in response to the detected input data type, reduces significantly the process time to search through a trie for matching data strings.

Abstract: Decoding and encoding of variable length data words and data strings is accelerated by testing for and processing more than one word or string per encoding or decoding cycle. In an encoding scheme wherein fixed length data words are encoded into variable length data strings, decoding is carried out by first receiving a data stream having a plurality of encoded data strings contained therein, and then testing at least a portion of the data stream to determine whether the portion contains one of a number of selected sets of multiple data strings. If the portion of the data stream contains one of the selected sets of multiple data strings, the multiple data strings are decoded into a corresponding set of multiple data words. This decoding procedure allows a plurality of encoded data strings to be decoded in a single decoding cycle. The procedure may be implemented using either a single lookup table or a set of split-level lookup tables.

Abstract: Data packets which have been sequentially encoded and transmitted, and are received out-of-sequence, are decoded, such that the proper sequence is restored. A receiving decoder is synchronized with a transmitting encoder and generates a sequence of decoding data corresponding to the sequence used to encode the data. The decoding data is combined with the received encoded data to produce the original dam. The decoded data is then stored in message-sequence in a memory. When packet network routing results in the encoded data being received out-of-sequence, a portion of the generated sequence of decoding data corresponding to packets that have not been received is saved in a memory. When the out-of-sequence packet of encoded data is received, the stored portion of the decoding data is retrieved from memory and is combined with the packet data to produce the decoded data, which is then stored in message sequence.

Abstract: A composite dictionary data compression process for use with a computer system comprising the steps of: receiving into the computer system an uncompressed input data string; searching a composite dictionary to detect for a dictionary data string matching the uncompressed input data string, the composite dictionary comprising a fixed dictionary and an adaptive dictionary; and modifying the adaptive dictionary in response to whether a matching dictionary data string is detected.

Abstract: A data compression process and system that identifies the data type of an input data stream and then selects in response to the identified data type at least one data compression method from a set of data compression methods that provides an optimal compression ratio for that particular data type, thus maximizing the compression ratio for that input data stream. Moreover, the data compression process also provides means to alter the rate of compression during data compression for added flexibility and data compression efficiency. Furthermore, a system memory allocation process is also provided to allow system or user control over the amount of system memory to be allocated for the memory intensive data compression process. System memory allocation process estimates the memory requirement to compress the input data stream, and allocates only that amount of system memory as needed by the data compression for memory allocation efficiency.

Abstract: An apparatus and method for processing video data for compression/decompression in real-time. The apparatus comprises a plurality of compute modules, in a preferred embodiment, for a total of four compute modules coupled in parallel. Each of the compute modules has a processor, dual port memory, scratch-pad memory, and an arbitration mechanism. A first bus couples the compute modules and a host processor. Lastly, the device comprises a shared memory which is coupled to the host processor and to the compute modules with a second bus. The method handles assigning portions of the image for each of the processors to operate upon.

Abstract: An apparatus and method for improving the security of an electronic codebook encryption scheme comprises a transmitter unit for encoding or encrypting data and a separate authorized receiver for decoding or decrypting data. Both the transmitter and receiver share a common secret key that has been communicated through a separate channel.The transmitter includes a Mapping Table (MTable) that comprises a table of functions, where a first series of incrementally numbered expressions are equated with a second series of randomly generated numbers. The plaintext is input into the transmitter and applied to the MTable to provide ciphertext. The PN generator supplies a unique random sequence of binary digits. The ciphertext byte and random number byte associated with each byte of plaintext data are exchanged to change the relationships within the MTable.

Abstract: A method and apparatus for compressing inherently redundant data. A Unicode file is comprised of prefix group indicator bytes and suffix character indicator bytes and can therefore be separated into two files, one containing the prefixes and one containing the suffix characters. Then, each separate file can be separately compressed using means best suited to the characteristics of each. Because of the high degree of redundancy across the prefix group indicator bytes they can be more greatly compressed which in turn results in greater compression of the entire Unicode file. Multiple compression methodologies, equally applicable to any inherently redundant data file, can be applied to the prefix group indicator bytes to yield the best compression results. In the present invention, one commonly occurring byte, known as the master byte, is chosen and each exception to the master byte in the data file to be compressed is noted by location (l) and value (v) thus reducing the overall size of the data file.

Abstract: A method and apparatus for improving the security of an electronic codebook encryption scheme comprises a transmitter unit for encoding or encrypting data and a separate authorized receiver for decoding or decrypting the data. During the encryption of the plaintext data, a randomly generated offset is introduced into the PN sequence to vary the starting point of the PN sequence as it is applied to the plaintext data. The offset is encrypted with the secret key and the unencrypted IV, encrypted offset, and ciphertext are exported by the transmitter to the receiver for decrypting.The encoded communication is imported by the receiver and the encrypted offset portion is extracted. The receiver combines the encrypted offset with the secret key to decipher the offset value. The offset and PN sequence are then combined with the ciphertext, using an XOR gate, to recover the original plain text from the ciphertext.

Abstract: An improved multi-codebook phase-in coding process for coding electronic data wherein for each received electronic input data, the coding process detects whether that input data exceeds a current coding maximum, then selecting a codebook coding method from one or more codebook coding methods in response to detecting whether that input data exceeds the current coding maximum, and then encoding that input data in accordance to the selected codebook coding method to generate a coded output data. A corresponding codebook indicator is inserted into a generated coded output data stream to indicate which codebook method to use to decode the coded output data. During decoding, the decoding process detects for a decode method indicator associated with each encoded input data, and decodes in accordance to a decode method corresponding to the detected decode method indicator to generate a decoded output data.